A sol-gel reaction involving phase separation has conventionally been known as a method for obtaining a monolithic porous material having continuous though-holes with controlled sizes in an organic-inorganic hybrid system using an oxide such as silica or titania, and a trifunctional alkoxysilane as starting materials (see Patent Documents 1 and 2). However, in those porous bodies, elastic modulus of a gel is extremely low, and brittleness is high as a whole. Therefore, it was difficult to impart flexibility withstanding large deformation to the porous bodies.
In view of the conventional problems, studies on a monolithic porous material further having high flexibility are proceeding. Patent Document 3 describes the preparation of a silicone monolithic body of an aerogel or xerogel having continuously penetrating flow channels and a silicone skeleton capable of dissolving chemical species by using both a bifunctional group-containing alkoxysilane and a trifunctional group-containing alkoxysilane or trifunctional or higher group-containing alkoxysilane as staring materials, copolymerizing those silanes by a sol-gel reaction, forming a network by Si—O bonds and simultaneously performing phase separation. Patent Document 3 further describes that the silicone monolithic body has both high flexibility and high porosity.